In the traditional pruning shears the means for providing mechanical advantage from the movement of a handle to the movement of the blade is located in the cutting head close to the blade.
A problem with the traditional pruning shears is that the means for providing mechanical advantage makes the cutting head big and heavy, thus hindering the usage of the pruning shears. Heavy weight positioned at the end of a long arm makes the pruning shears difficult to handle. On the other hand a big cutting head makes it difficult to fit the cutting head between branches to a desired position.
Another problem is that the efficiency of the traditional pruning shears is usually low. Plain sheave bearings and small sheave diameter compared to rope diameter result in loss of energy, which is usually about 50%. They also comprise many parts, thus making them complex, expensive to assemble and challenging to maintenance.